The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Mechanical joints between sections of metallic tubing are necessary in order to provide for ease of joining during assembly of high pressure gas lines. For applications involving gas temperatures less than 1300° F., sections can be joined using metal fittings that rely on elastic deflection of internal sealing surfaces. Such “dynamic seal” fittings cannot be used at temperatures above 1300° F. because the internal sealing surfaces plastically deform and permanently set into their deflected shape, loosing their elasticity and ability to provide a leak-free seal.
To achieve leak-free joints in high temperature (i.e., above 1300° F.) pressurized gas lines, it has typically been necessary to resort to fusion welding. Use of conventional fusion welding operations to join tube segments requires sufficient 360° access to the full circumference of the tube joint to accommodate manual or automated orbital fusion welding equipment. In applications that require dense packing to conserve volume and minimize weight, providing such access often results in suboptimum packing designs that unduly penalize the performance of end items that are weight and/or size critical. Examples of end items where low weight and size are critical include high performance aircraft and high performance missile systems and propulsion systems such as turbine engines.